The present invention relates to a timing device having a switchable light source for stroboscopically illuminating a rotating engine part, such as a crankshaft damper, in response to a signal from either an ignition system component, such as a sparkplug lead, or from another sensor, which could, for example, be a pressure sensor associated with a fuel injection system. The timing signal could alternatively originate from other components having a periodic characteristic corresponding to an engine operating parameter. The stroboscopic illumination produced by the present device permits an engine function to be timed with respect to the rotational position of an engine's crankshaft, camshaft, or other rotating part.
Timing lights have been used with sparked-ignited automotive engines for many decades. Such lights typically are hand-held devices powered by the engine's electrical system, (usually operating at twelve volts) and use an inductive pickup to trigger a neon light. Such timing lights suffer from the drawback that they are generally hand-held, thereby leaving the light's operator with only one free hand to adjust the engine. This situation is of moderate consequence for operators of ordinary production engines, because ignition timing is usually set while the engine is idling.
High performance engine applications present a different set of requirements regarding spark timing. With high performance engines, it is frequently desirable to determine total spark advance, and this is done only after opening the throttle so as to increase the engine speed. Of course, this requires one hand to rotate the distributor, and one hand to advance the throttle, leaving no means for handling a conventional timing light.
Hand-held timing lights suffer from an additional disadvantage because they are subject to damage from rotating machinery associated with the front end accessory drives of engines, such as a cooling fan. Hand-held timing lights also subject the operator to a risk of becoming entangled in the engine's drive belts. A timing device according to the present invention allows hands-free operation, and is useful for not only spark-ignited engines, but also diesel engines and other types of reciprocating internal combustion engines.